I like I2P, there's the official app, a lot of people I know seem to use InviZible though on Android.

Other alternatives to them are small and far between. There is Lokinet but it's tied to some other cryptocurrency for some reason. Any network where you participate in will obviously have participant nodes who are operated with a malicious intent. Splitting connections apart like onion routing does and encryption is the best you can do. It's also more susceptible to this problem the less participants there are.